Seal for reciprocating machine elements

ABSTRACT

A sealing arrangement for machine elements reciprocable relative to each other and defining with each other a gap to be sealed, in which barrier chamber means extend to said gap and contain a barrier substance intermixed with solid particles having a minimum diameter which is in excess of the width of said gap to be sealed.

United States Patent Musketa A 451 May 9, 1972 [541 SEAL FOR RECIPROCATING MACHINE ELEMENTS [72! Inventor: Alfred Musketa, Bergisch-Gladbach, Germany [73] Assignee: Klochner-Humboldt-DeutzAktlengesellschait, Cologne Deutz. Germany [22] Filed: Nov. 23, 1970 21 Appl. No.: 91,752

[30] Foreign Application Priority Data Dec. 3, 1969 Germany ..P 19 60 576.6

[52] U.S.Cl ..417/437, 92/83,)2/155, 184/1 E [51] int. Cl ..F04b 19/22, FOlm 1/00, F15b 21/04 [58] Field oiSearcli ..417/437; 92/83, 153,155; 184/1 E [56] References Cited UNITED STATES PATENTS 1.218.132 3/1917 Tuhey ..92/l53 1,679,140 7/1928 Graham ..92/ l 53 1,964,671 6/1934 Nesbitt .....92/155 2,225,815 12/1940 Acheson... ...184/] E 2,426,613 9/1947 Jackson ...92/153 2.795.195 6/1957 Amblard et al. ...417/437 2.922.491 1/1960 Macks ...l84/1 E 3,414,084 12/1968 Bues et a1 ..l84/l E FCRElGN PATENTS OR APPLICATIONS 351,707 7/1931 GreatBritain ..92/l53 847,541 9/1960 Great Britain ..l84/1E Primary Examiner-Henry F. Raduazo Attorney-Walter Becker 5 7 ABSTRACT A sealing arrangement for machine elements reciprocable relative to each other and defining with each other a gap to be sealed, in which barrier chamber means extend to said gap and contain a barrier substance intermixed with solid particles having a minimum diameter which is in excess of the width of said gap to be sealed.

6 Claims, 1 Drawing Figure SEAL FOR RECIPROCATING MACHINE ELEMENTS The present invention relates to a seal for reciprocating machine elements, especially pump pistons of a fuel injection pump, in which at the gap to be sealed there is provided a barrier chamber extending over the circumference of the respective machine element and filled with a barrier substance.

As barrier substance there may be employed a gas or a liquid which is so selected with regard to the media to be separated from each other that the barrier substance will not cause any damage. The drawback inherent to the sealing by means of a barrier substance consists in that the losses of the barrier substance through the gap to be sealed have to be replaced. This requires additional elements. Furthermore, the leakage losses of the barrier substance, as a rule, represent foreign substances for the media to be separated from each other, and such foreign substances must be held within certain limits in order to avoid disadvantageous effects. The seal of reciprocating machine elements is particularly difi'lcult inasmuch as, due to the translatory movement, barrier substance is conveyed from the seal into the media to -be separated from each other.

It is, therefore, an object of the present invention to provide a seal for reciprocating machine elements which will overcome the above mentioned drawbacks.

It is another object of this invention to provide a seal for reciprocating machine elements in which the losses of barrier substance during the operation of the reciprocating machine elements will be very slight.

It is still a further object of this invention to provide a sea] as set forth in the preceding paragraphs which will cause only very slight friction losses and in which the sealing effect can be increased without additional structural elements.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawing illustrating the seal according to the invention in connection with a fuel injection pump shown in cross-section.

The seal according to the present invention is characterized primarily in that solid particles are admixed to the barrier substance while the smallest diameter of these solid particles is larger than the sealing gap.

With a seal according to the present invention, at the start of the operation, the barrier substance takes along the solid particles and deposits the same in the region of the sealing gap. After a short time, the number of solid particles which collect and closely engage any desired cross-sectional shape of the respective machine part is so great that a good seal is obtained and only a very minor quantity of barrier substance can escape through the gap toward the outside. in view of the loose collection of the smooth particles and their good adaptation to the shape of the respective machine element, no material increase in friction looses occurs. Experience has shown that solid particles having a granular size of a diameter amounting to from ten to twenty times the sealing width of the sealing gap will bring about highly satisfactory results.

According to a further development of the invention, it is suggested to employ particles which will swell in the barrier substance. In this way a better contact of the particles with each other and with the respective machine part is obtained.

According to a still further development of the present invention, it is suggested to provide a reservoir for the barrier substance adjacent to the barrier chamber. In this instance the barrier substance is in the reservoir preferably kept under pressure so that the solid particles will also during operation firmly contact the respective machine part. The said pressure may be produced in the reservoir by a manually operable pump or by a spring-loaded piston or by an air spring. However, it may also be expedient according to a further suggestion of the invention to provide a pump driven by the cam of the fuel injection pump which first mentioned pump conveys the barrier substance into the reservoir while a check valve is interposed in the pressure line.

Referring now to the drawing-in detail, the fuel injection pump illustrated therein comprises a pump housing 1' having a cylindrical member 2 inserted therein in which a pump piston 3 is reciprocable. Pump piston 3 is actuated by a cam 4 against the thrust of a spring 5 and feeds fuel through a supply bore 6 and a relief valve 7 into the fuel pressure line 8. Between the chambers containing fuel and the chambers containing lubricating oil within the range of the cam 4 there are provided barrier chambers 9 for sealing the circumferential surface of the pump piston 3 relative to the cylindrical member 2, said barrier chambers 9 being filled with a barrier substance. The barrier chambers 9 communicate through a connecting bore 10 with a reservoir 11. Solid particles 12 are admixed to the barrier substance in the reservoir 11 and in the barrier chambers 9, which particles 12 may consist of suitable synthetic substances or sealing materials. The solid particles 12 expediently have a granular size of a diameter equalling from 10 to 20 times the width of the gap to be sealed between the respective machine elements.

The reservoir 11 is confined at the top by aspring-loaded piston 13 and has one circumferential side provided with a feeding passage 14 for the barrier substance. In addition to actuating the pump piston 3, cam 4 actuates a further springloaded piston 15 of an auxiliary pump which feeds the barrier substance, in this particular illustrated example the lubricating oil, through the feeding passage 14 into the reservoir 11. In the feeding passage 14 at the suction side and at the pressure side of the pump piston 15 there are provided check valves 16. Furthermore, a pressure limiting or relief valve 17 is arranged on the pressure side of pump piston 15.

As an example for the barrier substance which may be used in connection with the present invention, there may be mentioned any standard bearing grease or any standard lubricant. As solid particles 12 which may be admixed, may be mentioned solid particles of polytetrafluorethylene (PT F E), polyamide and wood dust or wood powder, or leather dust or leather powder.

It is, of course, to be understood that the present invention is, by no means, limited to the particular example shown in the drawing but also comprises any modifications within the scope of the appended claims.

What i claim is:

1. In combination: a first member, a second member, said first and second members being reciprocable relative to each other and together with each other defining a sealing gap to be sealed, barrier chamber means communicating with said sealing gap, and a barrier substance contained in said barrier chamber means and having solid particles intermixed therewith, the smallest diameter of said solid particles being in excess of the width of said sealing gap.

2. The combination according to claim 1, in which said solid particles have a granular size with a diameter equaling from about 10 to 20 times the width of said sealing gap.

3. The combination according to claim 1 in which said solid particles are of the type which swells in said barrier substance.

4. The combination according to claim 1, in which said bar.-

rier chamber means includes a reservoir containing barrier substance intermixed with said solid particles.

5. The combination according to claim 4, which includes pressure exerting means associated with said reservoir for maintaining the barrier substance in said reservoir under pressure.

6. A fuel injection pump which includes a cylinder, a plunger reciprocable-in said cylinder, said cylinder having its inner surface provided with circular groove means surrounding said plunger, cam means operable to activate said plunger, a reservoir containing a barrier substance intermixed with solid particles, the smallest diameter of which is in excess of the width of the play between said plunger and said cylinder, first conduit means leading from said reservoir with said groove means, second conduit means adapted to be connected to a source of barrier substance and leading to said reservoir, piston means associated with said second conduit means and operable by said cam means for pumping barrier substance into said reservoir, and pressure relief valve means interposed in said second conduit means. 

1. In combination: a first member, a second member, said first and second members being reciprocable relative to each other and together with each other defining a sealing gap to be sealed, barrier chamber means communicating with said sealing gap, and a barrier substance contaIned in said barrier chamber means and having solid particles intermixed therewith, the smallest diameter of said solid particles being in excess of the width of said sealing gap.
 2. The combination according to claim 1, in which said solid particles have a granular size with a diameter equaling from about 10 to 20 times the width of said sealing gap.
 3. The combination according to claim 1, in which said solid particles are of the type which swells in said barrier substance.
 4. The combination according to claim 1, in which said barrier chamber means includes a reservoir containing barrier substance intermixed with said solid particles.
 5. The combination according to claim 4, which includes pressure exerting means associated with said reservoir for maintaining the barrier substance in said reservoir under pressure.
 6. A fuel injection pump which includes a cylinder, a plunger reciprocable in said cylinder, said cylinder having its inner surface provided with circular groove means surrounding said plunger, cam means operable to activate said plunger, a reservoir containing a barrier substance intermixed with solid particles, the smallest diameter of which is in excess of the width of the play between said plunger and said cylinder, first conduit means leading from said reservoir with said groove means, second conduit means adapted to be connected to a source of barrier substance and leading to said reservoir, piston means associated with said second conduit means and operable by said cam means for pumping barrier substance into said reservoir, and pressure relief valve means interposed in said second conduit means. 